Ulcerative colitis (UC) is a relapsing form of inflammatory bowel disease (IBD) that is characterized by chronic inflammation of the colon. Those with UC may experience blood or mucous in the stool, abdominal cramping, weight loss, anemia and abnormally rapid heart rate in more severe cases.

Previous studies have concluded that vitamin D levels can be considered an environmental risk factor for IBD. Research has also shown that vitamin D deficiency is highly prevalent in both Crohn’s disease and UC. Additionally, researchers have linked the effects of vitamin D supplementation with disease severity and relapse in patients with IBD. However, little research has been conducted exploring the relationship between serum 25(OH)D levels and mucosal inflammation in patients with UC.

Due to vitamin D’s anti-inflammatory effects, it was hypothesized that serum 25(OH)D levels may affect the mucosal inflammation found in UC. In addition, vitamin D may protect against UC by mediating intestinal epithelial cell barrier integrity by preventing apoptosis (programmed cell death).

Recently, researchers analyzed the relationship between serum 25(OH)D levels and mucosal inflammation in order to determine if vitamin D may play a role in disease activity among those with UC. A group of 230 individuals with UC were included in the study. Serum 25(OH)D levels were measured at baseline and compared to patients’ Mayo score. Mayo score is a standard tool used to determine the disease activity in patients with UC, with a higher score indicating a more severe disease state.

After all tests were completed, this is what the researchers found:

Mean serum 25(OH)D levels at baseline was 21.8 ng/ml.

There was a significant inverse association between 25(OH)D concentration and mucosal inflammation, characterized by the Mayo endoscopy score (P=0.01), disease activity determined by the total Mayo score (P=0.01) and histologic activity (P=0.02).

Patients with no or little histological activity had significantly higher vitamin D levels than patients with moderate to severe histological activity. A higher histological activity indicates elevated levels of inflammation.

The researchers concluded:

“…patients with UC have a high prevalence of 25(OH)D concentrations <20 ng/mL, and a decrease in serum 25(OH)D concentration is associated with increased disease activity.”

They continued on to state:

“Given the known association between vitamin D deficiency with impaired calcium homeostasis, bone metabolism, and immune function, these findings support the routine monitoring of 25(OH)D concentrations and treatment of vitamin D deficiency in patients with UC, including those with inactive disease.”

It is important to note that this study’s observational design limits the overall strength of the study, as the researchers were only able to prove association, not causation. Further studies with stronger designs are needed in order to understand whether vitamin D reduces disease activity of UC by decreasing mucosal inflammation.